Many portable consumer and professional audio devices utilize headphones in order to provide audio content to a user. The headphones typically include two earpieces that are worn over the ears of users and that are coupled to the stereo audio channels of an audio device. Alternatively, the two earpieces may share a single audio channel or need no audio channel at all, as in the case of noise-reducing headphones. Each earpiece includes an ear cup in which at least one loudspeaker (i.e., a sound-emitting transducer) is disposed. More and more active circuits that provide, for example, active noise control (ANC) or wireless signal transmission are also included in the earpieces (or may be carried separately) to form active headphones. Active headphones are often battery-powered and include an on-off switch to turn them on and off. One problem with battery-powered headphones, particularly those with automatic noise-reduction circuitry, concerns battery life. Users who have these headphones generally put on and take off their headphones many times, often forgetting to turn them off, thus wasting costly battery life. Moreover, for headphones that are used infrequently and that are stored for long times between uses, the turn-off problem is worse, not only because their batteries are more apt to die, but because charging the batteries or finding fresh batteries is too often inconvenient.